Fix travis config to use guzzle/guzzle

Author: TiGR

.travis.yml

@@ -15,7 +15,7 @@ env:
 
 before_script:
   - composer require symfony/http-foundation:${SYMFONY_VERSION} --no-update
-  - composer require guzzle/http:${GUZZLE_VERSION} --no-update
+  - composer require guzzle/guzzle:${GUZZLE_VERSION} --no-update
   - composer install -n --dev --prefer-source
 
 script: vendor/bin/phpcs --standard=PSR2 src && vendor/bin/phpunit --coverage-text